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Subject[PATCH V2 2/2] regulator: pwm: Add ramp delay for exponential voltage transition
Date
Some PWM regulator has the exponential transition in voltage change
as opposite to fixed slew-rate linear transition on other regulators.
For such PWM regulators, add support for handling the exponential
voltage ramp delay.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
CC: Douglas Anderson <dianders@chromium.org>
CC: Aleksandr Frid <afrid@nvidia.com>

---
This patch is continuation of discussion on patch
regulator: pwm: Fix regulator ramp delay for continuous mode
https://patchwork.kernel.org/patch/9216857/
where is it discussed to have separate property for PWM which has
exponential voltage transition.

Changes from V1:
- Use new DT property to finding that voltage ramp is exponential or
not and use flag for having fixed delay for all voltage change.
---
drivers/regulator/pwm-regulator.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)

diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
index 1b88e0e1..bcffeee 100644
--- a/drivers/regulator/pwm-regulator.c
+++ b/drivers/regulator/pwm-regulator.c
@@ -233,6 +233,24 @@ static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
return 0;
}

+/**
+ * Some of PWM regulators have exponential voltage ramp. On such PWM
+ * regulators, voltage settling time is same regardless of voltage
+ * level change.
+ */
+static int pwm_regulator_set_voltage_time(struct regulator_dev *rdev,
+ int old_uV, int new_uV)
+{
+ return rdev->constraints->ramp_delay;
+}
+
+static int pwm_regulator_set_voltage_time_sel(struct regulator_dev *rdev,
+ unsigned int old_selector,
+ unsigned int new_selector)
+{
+ return rdev->constraints->ramp_delay;
+}
+
static struct regulator_ops pwm_regulator_voltage_table_ops = {
.set_voltage_sel = pwm_regulator_set_voltage_sel,
.get_voltage_sel = pwm_regulator_get_voltage_sel,
@@ -294,17 +312,25 @@ static int pwm_regulator_init_table(struct platform_device *pdev,
drvdata->desc.ops = &drvdata->ops;
drvdata->desc.n_voltages = length / sizeof(*duty_cycle_table);

+ if (of_property_read_bool(np, "voltage-ramp-exponential"))
+ drvdata->ops.set_voltage_time_sel =
+ pwm_regulator_set_voltage_time_sel;
return 0;
}

static int pwm_regulator_init_continuous(struct platform_device *pdev,
struct pwm_regulator_data *drvdata)
{
+ struct device_node *np = pdev->dev.of_node;
u32 dutycycle_range[2] = { 0, 100 };
u32 dutycycle_unit = 100;

memcpy(&drvdata->ops, &pwm_regulator_voltage_continuous_ops,
sizeof(drvdata->ops));
+
+ if (of_property_read_bool(np, "voltage-ramp-exponential"))
+ drvdata->ops.set_voltage_time = pwm_regulator_set_voltage_time;
+
drvdata->desc.ops = &drvdata->ops;
drvdata->desc.continuous_voltage_range = true;

--
2.1.4
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